"COAX RF CHOKE"vs BALUN

[unit_399]

The following quote is from the SIGNALENGINEERING/ULTIMATE web site

"You can try to eliminate this situation (called "Common mode currents") by winding an "RF Choke". Wind about 6ft of RG-213 or RG-8 into a coil (6 to 8 turns). For RG-58 use 4ft with 6 to 8 turns. Wind the coax up, placing each turn right next to one another. Use electrical tape to secure turns together. You should place these as close to the antenna as possible. Right at the antenna coax connection point being optimum."

Does this really work? Is it as good as installing an actual Balun? I have my beam ready to put up, and I want to get it right the first time.

- 399

 

[74IN]

It works to stop common mode, but I can't say about the balun thing.

 

[W5LZ]

Coax chokes do work for reducing common mode stuff. And a coax choke can help with going from a balanced to unbalanced condition, what baluns do. Won't help with any impedance transformation ratio.
Baluns do work (balanced to unbalanced thingy), but first, is your beam balanced to start with? If it uses some type of matching device, gamma match, whatever, no, it isn't. If it's directly fed, yes it is, and a balun might be a good idea. If it uses one of those matching devices, you should adjust that device to do the impedance transformation, not put a balun in there. Good place for a coax choke though, maybe.
Just have to have a balun? Make it a 1:1 balun, and you'd better make it a big one cuz most are 'over-rated' as far as power handling is concerned.
- 'Doc

Can you tell I'm not a fan of baluns?